The present invention relates to an aggregate of electronic device chips, an electronic device chip, an aggregate of diffraction grating light modulators, and a diffraction grating light modulator.
An image-forming device, such as projector and printer, which is so designed as to form a two-dimensional image from a one-dimensional image displaying device by projecting a light beam onto an image forming means while scanning with a light scanning means, is known from Japanese patent Nos. 3401250 and 3164824. The one-dimensional image displaying device is composed of a plurality of diffraction grating light modulators (GLV: Grating Light Valve) which are arranged in an array pattern. Incidentally, this one-dimensional image displaying device is referred to as diffraction grating light modulator. The diffraction grating light modulator is produced by using the micromachine producing technology. It is included of reflective diffraction grating and it performs optical switching action. It forms an image as light is turned on and off electrically. In other words, the diffraction grating light modulator produces a two-dimensional image by scanning (with a scan mirror) the light beam emerging from the individual diffraction grating light modulating elements. Therefore, if a two-dimensional image composed of M×N pixels (for example, 1920×1080 pixels) is to be formed, it is necessary to construct the diffraction grating light modulator from N units (or 1080 units) of diffraction grating light modulating elements. Moreover, for color display, it is necessary to use three units of diffraction grating light modulators.
FIG. 6 is a schematic diagram illustrating diffraction grating light modulating elements 10 each having a lower electrode 12, fixed electrodes 21, and movable electrodes 22. Incidentally, hatching in FIG. 6 distinguishes the lower electrode 12, the fixed electrodes, 21, the movable electrode 22s, and the supports 14, 15, 17, and 18.
The diffraction grating light modulator 10 consists of the lower electrode 12, and elongate (ribbon-like) fixed electrodes 21, and the elongate (ribbon-like) movable electrodes 22. The lower electrode 12 is formed on the support 11. The fixed electrodes 21 are held by the supports 14 and 15, so that they are suspended and stretched above the lower electrode 12. Moreover, the movable electrodes 22 are held by the supports 17 and 18, so that they are suspended and stretched above the lower electrode 12 and are juxtaposed to the fixed electrodes 21. In the example shown, one diffraction grating light modulating unit 10 is composed of three fixed electrodes 21 and three movable electrodes 22. The three movable electrodes 22 are collectively connected to the control electrode, which is connected to a connecting terminal (not shown). On the other hand, the three fixed electrodes 21 are collectively connected to the bias electrode, which is common to a plurality of diffraction grating light modulating units 10 and which is grounded through a bias electrode terminal (not shown). The lower electrode 12 is also common to a plurality of diffraction grating light modulating units 10 and which is grounded through a lower electrode terminal (not shown).
When a voltage is applied to the movable electrodes 22 through the connecting terminal and control electrode and also a voltage is applied to the lower electrode 12 (which is actually grounded), an electrostatic force (Coulomb force) occurs between the movable electrodes 22 and the lower electrode 12. This electrostatic force moves the movable electrodes 22 downward or toward the lower electrode 12. The configuration of the movable electrodes 22 before displacement is shown in FIG. 7A and FIG. 10B (left side), and that after displacement is shown in FIG. 10A and FIG. 10B (right side). As the result of displacement of the movable electrodes 22, a diffraction grating of reflective type is formed by the movable electrodes 22 and the fixed electrodes 12.
The following relation is established among the distance (d) between adjacent fixed electrodes 21 (see FIG. 10B), the incident angle (θi) and the wavelength (λ) of the incoming light incident on the movable electrodes 22 and the fixed electrodes 21, and the angle of diffraction (θm)d[sin(θi)−sin(θm)]=m·λwhere m denotes an order, which assumes any number of 0, ±1, ±2, . . . .
The diffracted light has the maximum intensity when the difference (Δh1) between the top of the movable electrodes 22 and the top of the fixed electrodes 21 is equal to λ/4. (See FIG. 10B.)
FIG. 11 schematically shows an image forming device equipped with three units of the diffraction grating light modulators mentioned above. The image forming device has three light sources 100R, 100G, and 100B, which emit respectively a red laser beam (indicated by a dotted line), a green laser beam (indicated by a solid line), and a blue laser beam (indicated by a chain line), as primaries. The laser beams emerging from these light sources pass through condenser lenses (not shown) and enter respectively the diffraction grating light modulators 101R, 101G, and 101B. They are combined into one beam by the L-shape prism 102. The combined beam passes through the lens 103, the spatial filter 104, and the image forming lens (not shown). The beam is finally scanned by the scan mirror 105 and projected to the screen 106.
The image forming device mentioned above works as follows. When the diffraction grating light modulating element 10 is not in operation (or the movable electrodes 22 are in the state as shown in FIG. 7A and FIG. 10B (left side)), the light reflected by the top of the movable electrodes 22 and the fixed electrodes 21 is screened by the spatial filter 104. On the other hand, when the diffraction grating light modulating element 10 is in operation (or the movable electrodes 22 are in the state as shown in FIG. 10A and FIG. 10B (right side)), the light (with m=±1) reflected by the top of the movable electrodes 22 and the fixed electrodes 21 passes through the spatial filter 104. This construction permits the on-off control of the light to be projected to the screen 106. In addition, if the voltage to be applied to the movable electrodes 22 is properly varied, it is possible to change the difference (Δh1) between the movable electrodes 22 and the fixed electrodes 21 in the height of their tops.
With very small movable electrodes 22, the diffraction grating light modulator is capable of displaying with high resolution, rapid switching, and broad band. In addition, the movable electrodes 22 are operable with a low voltage and hence the diffraction grating light modulator will help realize a very small image forming device. Such an image forming device (which performs scanning with the scan mirror 105) produces a much smoother and more natural image than the ordinary two-dimensional image forming device of projection type that employs a liquid crystal panel. Moreover, the laser beam primaries reproduce natural colors which have never been attained.